Ion Drive
"Used to have a Felis type Engineer on board, went by the name Tony. Well anyway Worked out great till the Captain upgraded the engines from Chemical to Ion. See Cap scrimped a little on the insulation paneling, and retrofitting. First time we fired the drive on up 'POOF!' Ol' Tony's fur fluffed out like an Aldeberan pufferfish. Funniest thing yah ever saw. What happened to Tony you ask? Well after he complained to the Capt about the static discharge, the Capt suggested he could always shave, well when the cuts and bruises healed the Capt' put out the advert looking for a new engineer seeing as how Tony had so recently, and violently, resigned." ~Dankeen Sirious, Third officer Independant Freighter "Moira" ---- What it is A lot of drives use Electromagnetic forces for various effects of thrust. Modern level Ion drives make use of a gaseous form of elemental Charge Zero (Or Noble) gasses (Most often times stored in a pressurized liquid state and atomized before use) Or other type of low Ionization potential material (Like caesium or indium) which are Electromagnetically accelerated and primed for injection into the drive. Once injected into the drive the particles are charged creating Ionized particles with the removal of electrons by a central charged Anode. These Electrons travel along the anode and are released at the end of the tapering point, Whereas the Ionized particles are circularly accelerated by the magnetic fields along the length of the chamber building in velocity till they also are released in "pulses" by the Cathode at the exhaust nozzle. The expulsion of these ionized particles provides thrust for the vessel. Depending on the charge stored by the particles this can be anywhere from 30 to 350 or more pulses per standard second (Also regulated by the controls on how much acceleration is required). Alternately the exterior "walls" of the thrust chamber work as the Anode carrying the Electrons and the Ionzed mass is accelerated and compressed in the middle of the chamber. Though this design tends to be less fuel efficient (The same sized reaction nozzle doesn't quite get the same speed for the ionized particles per pulse) it is still widely used for Sublight thrust. Once expelled by the Cathode exhaust nozzle the Ionized particles and the electrons that were pulled free recombine as the electrical charge dissipates causing a bright glow or "halo" at the exhaust point. The then inert gas is left behind as interstellar particles. ---- Benefits and Disadvantages Cost of operation is a primary benefit of the Ion drive. The Inert Zero charge gasses primarily used as fuels are easily obtained (With a decent ramscoop and atmospheric processor they can even be obtained on primitive worlds without modern refinement facilities) and the power requirements for operating the array are well within even a modest reactor system's capabilities. In fact A lot of Ion drives can be operated at minimal power with even capacitor backup power systems, usually more than enough to keep the ship moving towards assistance in the event of a reactor problem. Waste is also a benefit, as the only real byproducts of the reaction are inert gasses, some minor thermal remnants and a bit of an Ionized charge that dissipates fairly rapidly once the drives are brought to a neutral or shut down state. (More primitive Ion drives used to be equipped with dispersion antenna which could hold a charge and arc from the antenna to nearby beings or ships if not properly discharged.) And even if heavier or non inert gases are used, the impact to environments is far less than with chemical or Impulse thrusters. Durability and maintenance are also advantages. Without a great many moving parts in the entire system, and not much heat (by comparison) generated the actual wear and tear on the system is mostly negligible. Other than alignment and adjustment of the magnetic field generators (Which can get mis-aligned due to vibrational stress or impact or simple time) most engineers claim all you have to do is make sure the fuel line is clean once a trip and you can collect your paycheck. Size to thrust ratio is a drawback of Ion drives. Under most current systems, there is a maximum size the drive can be and still be efficient. (Effectiveness drops off dramatically if you go bigger and bigger on the drive chamber.) Which means there is a maximum thrust available for each unit. Most larger ships that utilize Ion drives will have multiple units operating in parallel, this does, also, mean a larger mass required for fuel storage as well as more space for the drives. The use of the drives leaves behind a very specific signature of still ionized and inert particles which over time will disperse, however depending on the system, this may take anywhere from a couple of hours to a couple of days. For those who may not wish to leave behind a trail as they move through a system, this can cause problems. Likewise most pirate ships will use a spectrum scanner to pick out the most recent trails at a transit point and can follow that trail all the way to the ship. (It is possible in the above case to baffle the sensors of a perusing ship. Ionic dispersion emitters are usually seen as illegal in most civilized systems, and are near impossible to hide, though some captains have managed such with really ornate tail fins or nacelles. Other methods have been figured out over time, one of the most effective is to baffle the ion drive, (or lessen the output of thrust by lowering the compression rate but release more of the charged fuel out the nozzles (Alternately an emergency dump of a fuel tank can also work)) and then target the concentrated area with energy weapons on maximum dispersion which, in many cases, will super-charge the excess fuel in the area and disperse it all over a wide expanding spherical area, making the trail suddenly dissipate. if done at the same point where one changes course to a new heading a lot of pursuit craft can spend days searching for where the trail picks up again.) Powering up is another drawback of using an Ion drive. The system isn't capable of going from full shutdown to full power without a period where it needs to charge up and build up a sufficient speed and ionized particle mass for use. And there is really no way to hurry this process along. Many captains will choose not to power down fully unless they are spending an extended time somewhere, instead put the engines into a form of standby mode where the electromagnetic fields will continue running, and minimal amounts (a few atoms or so) of fuel will be run through the system to keep the drive charged, and without the final compression these atoms will just make their way out the exhaust with no real thrust provided. Some local regulations require engines be brought to a complete shut-down state while landed or docked so captains are advised to check on those before deciding to go into standby mode.